Tuning mechanism for wireless sets



March 26, 1946.4

' c. L. RICHARDS 2,397,435 TUNING MECHAYNISM FOR WIRELESS SETS Filed Ju'ly 12, 1944 2 sheets-sheet 1 .5'. s CLAUDE 'ANGDoA//P/cf/APDS.

March 26, .1946. c. L. RICHARDS TUNING MECHANISM FOR WIRELESS SETS 'Filed July 12, 1944 2 sheets-sheet 2 .4 iorney Patented Mar. 26, 1946 TUNING MECHANISM FOR WIRELESS SETS Claude Langdon Richards, London, England, as-

signor to The Hartford National Bank and Trust Company, Hartford, Conn., as trustee Application July 12, 1944, Serial No. 544,607 In Great Britain March 9, 1943 v7 claims. (o1. 'r4-10) In wireless sets it is sometimes desirable to be able to set the tuning member l(condenser or vinductance) rapidly to a predetermined position so as to tune to the corresponding wavelength without the exercise'of care and attention. When tuning is eifected by rotation of a shaft which, for example carries the moving vanes of a variable condenser, this result can be achieved by a so-called click system in which by spring action a lever on one component is urged into engagement with a notch-like recess in another component, one component being stationary while the other is fixed to and rotates with the shaft. For accurate tuning it is necessary for the lever toy seat in a predetermined position in engagement with both wallsV of the recess.

Due to considerations of convenience in tuning, appearance of the cabinet housing the wireless set, and the circuit design determining the location of the components within the set, the tuning knob or member which hask to be operated to tune the set is usually not in alignment with the shaft to be rotated to effect the tuning, and the tuning indicator or wavelength scale may also be remote from both tuning knob and the said shaft. A driving connection such as a cord system has therefore to be provided between the tuning knob and the shaft and perhaps between the latter and the indicator. This adds to the weight of the parts to be moved and the frictional resistance to be overcome during the tuning operation. As a result it is diflicult to ensure that proper engagement is obtained in a click system, as the spring effecting the click engagement cannot conveniently be made powerful enough.

The object of the present invention is to ensure that proper click engagement is obtained irrespective of the relative positions of the ccmponents. According to the present invention and with this object in view the driving connection between the tuning knob and the tuning shaft which normally is arranged to be ysubstantially without play is modified when a click lever encounters a click notch and as a result of this modification a limited amount of play is introduced into the driving connection to enable the click spring to move the click lever into full engagement with the click notch and thereby to bring the shaft into the predetermined tuned position without having at the same time to impart a corresponding movement to the tuning knob through the driving connection. In other words, during the .click action and in order to enable it to be completed provi-sion is made for temporarily releasing the tuning shaft from its normal driving connection.

. This result can be achieved in various ways and various mechanisms suitable for the purpose will be hereinafter described with reference to the accompanying drawings, by way of example.

In the drawings:

l Fig, l is a diagrammatic representation of a typical tuning arrangement to which the present invention is directed;

Fig. 2 is a fragmentary face view (substantially along the line II--II of 'Fig. 3) of a mechanism according to the invention for incorporation in a tuning arrangement according to Fig. 1;

Fig. 3 is a side view corresponding to Fig. 2;

Fig. 4 is a semi-diagrammatic representation of Vanother tuning mechanism according to the invention; I

Fig. 5 is a fragmentary View showing a detail of Fig. 4 on an enlarged scale;

Fig. 6 is a semi-diagrammatic representation of a third tuning mechanism according to the invention.

Referring first to Fig. 1, the tuning knob I is connected .to a pulley or drum `2 within the casing of the set. From the pulley 2, `a driving belt or cord 3 extends round a further pulley or drum 4 whereby the drive is imparted to a shaft 5, and thence, for example to the movable vanes of a tuning condenser. `The cord 3 carries a tuning indicator 'l which is caused to move over the tuning scale 6. The elements I0, II indicated in Fig. 1 form part of the mechanism which will now be described more fully with reference to Figs. 2 and 3; the indication in Fig. 1 serves to show how the mechanism of Figs. 2 and 3 is incorporated in an arrangement according to Fig. 1.

In Figs. 2 and A3, the shaft 5 is assumed to be operated by an arrangement as described above with reference to Fig. 1. This shaft 5 carries an arm or disc 9, which in practice may be constituted by the pulley 4 (Fig. 1). Provided in the disc 9 is an aperture Ill which as shown is of triangular form, the triangle being symmetrical about a radial line through the shaft 5 and 'the width of the aperture increasing with decreasing radial distance. The shaft 5 is coaxial with a shaft 'I5 constituting the actual tuning shaft, said shaft 5 thereby servingas a driving shaft for the driven shaft I5.v Secured to the shaft I5 is an arm I4. Pivoted on a pin I3 on the arm I4 near its outer extremity is a bell crank lever I2 car- I and extends into the aperture I0 in the disc 9.' A spring I'o anchored to a post I8 on the arm I4 and to a post I'I on the lever'l2 tends to Vrock the lever I2 so as to urge the pin II away from theishaft I5, i. e. into the narrowV outer Vportion of the aperture I0. Thus in the absence of furtherconstraint, the pin II is caused to engage in this narrow portion where it is in contact with both walls of the aperture, so that the arm Mis entrained by the disc 9 in either sense of rotation and the shaft' 'I5 rotates with the,

shaft 5. Y'

The click device for locating the shaft I5 in a predetermined setting consists of a click plate I9 which can be secured in adjusted position on a supporting rail by means of a bolt 22 passing c through a slot 2I in the plate i9. The'pin II in this construction is utilised as the clickpinand the spring Ilias the click spring. The inner face of the plate I9 has a click notch 24 adapted to receive the pin I I and thereby to locate the shaft I5. On either side of the notch 24 Ythe plate I9 exhibits cam surfaces "23, which as the arm YIll approaches the click position depress the pin II and rock the lever I2 .against the action of the spring I5. 'Y'Ihepin II is thus moved into the wider part of the aperture I0 vand is driven by the engagement of one side of the aperture I0.

when the notch 28 is opposite the pin 3U the spring urges the pin into the notch, thereby holding the a predeterat the inner apex of the diamond-shaped aper- Yture I0, so that the pin follows the rotary movef ment of the plates in both senses of rotation.V

When, however, a click pin 30 encounters the end of the plate 3l, it displaces the latter against the action off, the spring 32 thereby moving the pin I I into the'wide part ofthe aperture I0, so that the disc 2'I can be rotated by the action of the pin 30 on the entrance throat to the slot 28. When the slot 28 is fully in alignment, the pin 3i) can enter 'the substantially parallel sided inner portionY of the slot, thereby giving precise location of the disc 21. The pin IIy in this movement is shifted towards the outer apex of the aperture IQ. Consequently, when the drum I is rotated for re-tuning, `one ofthe inclined walls ofthe aperture I0 adjacent its outer apex encounters the pin II land by a cam-like action displaces it inwardly thereby moving the click pin 30 out into the throat portion of the slot 28. The pin SII can then ride-back on to the periphery of the disc Hand-the latter is free to participate in the Y the pin II in the apertureV Iii, two blade springs click position there is play between the walls of the play is eliminated.

Although only one click member I9v is shown in Fig. 2, a plurality of click members will in practice be provided such additional click members being distributed about the axis of the tuning shaft in accordance with the desiredpredetermined settings of thertuning shaft.

In the arrangement which will now be described with reference to Figs, 4 and 5, those parts which correspond with elements already described with reference to Figs. 1 to 3 are indicated by the same numerals as in those figures. The tuning knob'l is connectedwith a drum 2 from which the drive is transmitted to a-V drum 4 by means of a cord 3.3 The drive is further transmitted to a separate tuningindicator (not shown) by a connection indicated by arrows 26. Mounted with the drum 4 is a plates with an aperture I0 in which engages a pin IIwhereby the rotation-is transmitted to the tuning shaft is. Y

Secured tor the shaft|5 is a disc 2'I provided in its periphery with a single notch or recess 28. As best seen from Fig. 5, the recess comprises an inner substantially parallel walled section and an outer section which diverges and merges in a smooth curve into the circular periphery. Pivotally mounted on a circular support 2D are levers carrying stop pins and spring urged towards the disc 21. One such lever 2S and its stop pin 30 are shown inFig. 4. lA spring vl(not shown) urges it in the direction indicated by the arrow, so that 33 anchoredto the discs are provided which embrace the pin II.

In the arrangement as shown in Figs. 4 and 5, the click .mechanism can readily be disabled and simple tuning resorted to by the provision of means acting on allthe levers 29 to hold them in such a position that the pins 52 are raised clear of the disc 21. .Y

V`In the modification shown in YFig. 6, .asingle lever 29 is provided, but the disc 2143s provided f with a plurality of slots 28 distributed through guides 35 is a plate 35 which is loaded by springs` 42 which tendfto maintain it in a position in which all the slots 28 are masked either by the plate itself, as by the masking edge 33, or b y levers 31 coupled with the plate 35. The arrangement is, such that when the pin 35 engages the edge 33011 a lever 31 at a recess 28, the spring loading on the pin 3i] overcomes the springs 42 and displaces the plate 35 into the position shown, so that the pin 36 can enter and seat against both faces of the recess. The drive is transmitted by way of a cam-like member 42 which is mounted on the driven shaft 5 and corresponds to the discs k9 of the embodimentsY described with reference to Figs. 2 to 5. The substantially semi-'circular driving end of the'cam member 4I is received by a corresponding aper ture inthe plate 35. The driving end of the cam 4I has a central projection or pip 44 which in the normal position of the plate 35 registers with an indent d and is held in engagement therewithr by the springs 42, thereby providing a positive drive to the tuning shaft. In theV displaced position of the plate 35 `as shown,.the positive connection between cam member 4l and plate 35 is released so that the disc 21 can perform a limited rotary movement relative to the driving arrangement. When however the cam member 4I is driven for re-tuning, one of the shoulders 43 thereon encounters the 'base of the opening in the plate 35 and displaces the latter against the action of the spring-loaded click lever 23 whereby the latter is moved out of the slot 28 in which it was engaged, Thereupon the springs 42 re-centre the plate 35 in relation to the cam member 4| so that the pip 44 re-enters the indent Ml and the positive drive is restored.

To render inoperative the positive stop or clickA mechanism of Fig. 6, it is merely necessary to rock the single click lever 29 out of engagement with the disc 2. In .this embodiment, as in that of Figs. 4 and 5, the operation of the stop mechanism can be controlled either by -a separate knob or by an in-,and-out movement of the tuning knob.

I claim:

1. An apparatus for adjusting a tuning shaft to a predetermined position, comprising a driving element, a driven element coupled to-said shaft, an eccentric coupled to one of said elements and engaging an aperture in the other of said elements to thereby couple said driving element to said shaft, said aperture having an apex portion and diverging wall portions, means to normally position said eccentric in engagement with the apex portion of said aperture, and means operative at positions of said shaft approximating the said predetermined position to positionsaid eccentric between said diverging wall portions of said aperture to thereby permit limited rotational movement of said eccentric within said aperture and to independently rotate said driven element within the limits of said limited rotational movement to thereby rotate said shaft to the predetermined position without simultaneously rotating said driving element.

2. An apparatus for adjusting a tuning shaft to a predetermined position, comprising a plateshaped driving element rotatable about an axis coextensive with the axis of said shaft and having an aperture therein, said aperture being positioned about a radial line extending from the center of rotation of said driving element and having its width increasing with decreasing radial distance from the axis of rotation of the driving element, a driven element rigidly secured to said shaft, an eccentric pin member coupled to said driven element and extending into said l aperture to thereby couple said driving element to said shaft, spring means to normally urge said pin outwardly into engagement with the narrow portion of said aperture, and a plate member arranged radially about the axis of said shaft in a predetermined position with respect to said axis, said plate member having two-spaced cam surfaces for engaging said pin at positions of said shaft approximating the said predetermined position and for inwardly deflecting said pin to thereby locate said pin in a wider portion of said aperture and permit limited rotational movement of said pin about the axis of said shaft within said aperture, and having al cam surface intermediate said spaced cam surfaces for engaging said pin and rotating said driven element within the limits of said limited rotational movement to thereby rotate said shaft without simultaneously rotating said driving element.

3. An apparatus for adjusting a tuning shaft to a predetermined position, comprising a platecoextensive with the axis ofsaid shaft and having a triangular aperture thereimsaid aperture :being positioned about a radial lineA extending from the center of rotation of said driving element andhaving its width increasing with decreasing radial ldistance from the axis of rotation of the driving element, a driven element rigidly secured to said shaft, an eccentric pin member coupled to said driven elementy andextending into said aperture to thereby couple said driving element to said shaft, spring means to vnormally kurge said' pin outwardly into engagement with the narrow portion of said aperture, and a plate member arranged radially about the axis of said shaft in a predetermined position with respect to said axis, said plate member having a. W- shaped cam surface the arms of which engage said pin at positions of the shaft approximating the said predetermined position and inwardly deflect said pin against the action' of said spring means to thereby locate said pin in a wider portion of said vaperture and permit limited rotational movement of said pin vabout the axis of said shaft within said aperture, and theV A- shaped portion of which engages said pin at positions of the shaft `intermediate said approximate positions to rotate said driven element within the limits of said limited rotational movement and thereby rotate said shaft to the predetermined position Without simultaneously rotating said driving element.

4, An apparatus for adjusting a tuning shaft to a predetermined position, comprising a plateshaped driving element rotatable about v an axis coextensive with'the .axis of said shaft and having an aperture therein, said aperture being arranged about a radial line extending from the axis' of said driving element and having an apex portion, Wall portions diverging from said apex portion with increasing radial distance from the axis of said drivin-g element and wall portions converging ,from said diverging Wall portion with increasing radial distance from the axis of said driving element, a disc-shaped member rigidly secured to said shaft and having a peripheral notch, a second member mounted on said disc member and displaceable along a diameter of the said disc member and having an end portion positionable over said notch-in the displaced position of the said second member, an eccentric pin member mounted on said second member and extending into said aperture to thereby couple said driving element to said shaft, spring means for displacing said second member` to thereby position the end of the said second member over the notch and to position said pin at .the apex portion of said aperture, a pin element engaging said second member at positions of the shaft approximating the said predetermined position for displacing said second member against the action of said spring means to thereby locate the eccentric' pin member between said converging wall portions of said aperture and permit limited rotational movement of the eccentric pin member within said aperture, said second pin member engaging said notch and rotating said disc-member independently of said driving element within the limits of said limited rotational movement to rotate said shaft to the predetermined position Without simultaneously rotating said driving element.

5. An apparatus for adjusting a tuning shaft to a predetermined position, comprising a discshaped driving element rotatable about its center coincident with the axis of the shaft and having i adjacent to said rst disc member, a plate member mounted on said second disc member 'between said disc members'a'nd movable along the diameter of said second disc member, an eccentric pin member mounted'on `said plateY member and extending Yinto said aperture, spring means to urge said platermember towards one end vposition thereof to thereby position the end of'said plate member over the notch and saidpin member inthe apex of said aperture, a pin element engaging said plate member at positions of the shaft approximating thesaid predetermined position for displacing said plate member against the action of said spring means to thereby locatesaid first pin member between said converging wall portions of said aperture and permit limited rotational movementaof said disc members relative to each other, said secondv pincmember engaging said notch at positions of the shaft approximating the predetermined position and rotating said second'disc member within the limits of said limited rotational movement to rotate said shaft to the predetermined position vwithout simultaneouslyv rotating said driving element. Y

6. An apparatus for adjusting a tuning shaft to a predetermined position, comprising a driving member having its axis of rotation coincident with the' axis of the'shaft, a disc-shaped driven meraber rigidly secured Vto said shaft-and having a notch at a predetermined location in its periphery, means to mask said notch comprising a plate member mounted on said disc'member, said plate member being displaceable along theV diameter Vof the said disc member and being provided with an aperture having an apex portion and wall portions diverging from said apex with decreasing radial distance from the axis of the disc, a

" cam member secured to said driving member and engaging said aperture, said cam member having an apex portion and diverging Wall portions,` a spring member for urging said plate member toward one end position thereof along the diameter of said disc to position the apex of the cam member in the apex of the aperture and to mask said notch, a pin member engaging the periphery of said disc, said pin member engaging said mask- I ing means at angular positions of the disc aping shaft to predetermined positions, comprising a driving member having its axis of rotation coincident with the axis of the shaft, a disc-shaped driven member secured to said shaft and having a plurality of notches at predetermined portions of its periphery corresponding to the said predetermined positions of the shaft, a plate'member mounted on said disc, said plate member be- VVing'displaceable along the diameter of said disc and being provided with an aperture having an apex portion and ywall portions diverging from said apex with decreasing radial distance from the axis of the disc, lever members mounted and pivoted on said disc and engagingV said plate member, said plate member and said lever members having portions thereof positionable over said notches to thereby mask said notches at one end position of the plate member, a cam member secured to said driving member and engaging saidr aperture and having an apex portion and diverging Wall portions, a spring member for urging said plate rmember to the said one end position thereof to position the apex of the cam member l in the apex of the aperture and the plate member 40 and the lever members over said notches, a pin member engaging the periphery of the discjsaid pin member selectively engaging said masking means at angular positions of the disc approximating a selected predetermined position of the shaft and displacing said plate member to thereby disengage the apex of the cam member from the apex of said aperture and permit limitedV rotational movementof said disc member relative to the driving member, said pin member further engaging the unmasked notch to rotate said disc within the limits of said limited rotational movement to thereby rotate said shaft to the selected predetermined position independently of the drivmg means.

CLAUDE LANGDON RICHARDS. 

